The (unsophisticated) idea that different types of blood might have different abilities to absorb oxygen/ different concentrations of red blood cells has me wondering!
Your question assumes that each blood type offers a different capacity to carry oxygen. Without going into scientific explanations, the easiest way to answer the question is to understand the role of Hemoglobin.
Hemoglobin is a protein that serves as a transport mechanism to deliver oxygen to the body tissues. VO2Max is a measurement of how quickly the body consumes that oxygen. While there are factors that can impact Hemoglobin's ability to carry oxygen (ie. disease and environment), blood type is not one of them. That's because blood types refer to the protein on the surface of the red blood cells. Hemoglobin is a solution inside the red blood cell membrane. Think of it in terms of a rubber water balloon. The rubber would be the membrane and the water is the hemoglobin. Blood types are properties of the membrane. The hemoglobin (inside) is the same regardless of the outer (protein) blood type. As such, the blood type is not a factor in VO2Max because it does not influence oxygen transport.